63 results about "Total protein" patented technology

The invention provides cream cheese and a preparation method thereof, and belongs to the technical field of dairy product processing. According to the method, firstly, raw milk is subjected to degreasing and membrane filtration concentration, the concentration multiple is controlled to be 1.5-4, the lactose content of the concentrated solution is precisely regulated and controlled to be 3-6.5% through washing filtration, and the raw milk concentrated solution rich in casein (accounting for 85-95% of total protein) is obtained. Then, mixing the concentrated solution with single cream, white granulated sugar and the like, homogenizing, sterilizing, inoculating a leavening agent and chymosin, fermenting, refrigerating and demulsifying to obtain a finished product. According to the invention, nutrition waste and environmental pollution caused by discharge of whey in a traditional process are fundamentally avoided through membrane filtration pretreatment, and meanwhile, the problems of pink feeling and peculiar smell caused by addition of milk protein powder are solved; the obtained product is pure and rich in flavor, fine and smooth in texture, simple and efficient in process and suitable for large-scale production.

The invention discloses a method for improving the solubility and thermal stability of sweet protein, and belongs to the technical field of biosynthesis, the method comprises the following steps: constructing a gene tandem recombinant plasmid containing a monellin x-3C-sfGFP-3C-monellin y expression cassette, x is greater than or equal to 1, y is greater than or equal to 1, 5 is greater than or equal to x + y is greater than or equal to 3, a 3C protease recognition sequence is also inserted between adjacent copies of monellin, and each monellin is connected with a purification tag; the gene tandem recombinant plasmid is transformed into escherichia coli and inducible expression is carried out, thalli are split and purified to obtain fusion protein, 3C protease is used for enzyme digestion, and the target protein is obtained after re-purification. The total protein yield and the solubility proportion are remarkably improved by adopting a series construction mode of plasmids, meanwhile, the stability of monellin is effectively improved, the purification step is simpler and more convenient, and the method is suitable for industrial production.

The invention provides modified milk powder capable of promoting bone health as well as a preparation method and application of the modified milk powder. The total protein content of the modified milk powder is 17-35 g / 100 g, the fat content of the modified milk powder is 1-32 g / 100 g, and the calcium content of the modified milk powder is 0.8-2.1 g / 100 g. Moreover, the modified milk powder contains bovine coloctrum and lactoferrin, the mass ratio of the bovine coloctrum to the lactoferrin is (5-100): 1 on the basis of the dry matter content, and the content of the lactoferrin in the modified milk powder is 2-400 mg / 100 g. The bovine colostrum and the lactoferrin are combined for preparing the milk powder, have a synergistic effect on promoting osteoblasts and inhibiting osteoclast proliferation, and are beneficial to bone health.

The invention discloses application of roxburgh rose exosomes in preparation of products for preventing and treating acute alcoholic liver injury, relates to extraction of the roxburgh rose exosomes and new application of the roxburgh rose exosomes in prevention and treatment of the acute alcoholic liver injury, and belongs to the technical field of biology. The roxburgh rose exosome can also prevent and treat acute alcoholic liver injury. The particle size of the roxburgh rose exosome is 135.2 nm, the particle concentration is 1.3 * 10 < 11 > Particle / mL, and the total protein concentration is 2.12 mu g / mu L. A new thought is provided for research and development of drugs for preventing and treating acute alcoholic liver injury, the extraction method of the roxburgh rose exosome is simple, full development and utilization of food resources can be promoted, and a drug or a health care product for preventing and treating acute alcoholic liver injury is provided.

The present application relates to the technical field of cell function detection, and particularly relates to a method for evaluating cell function of HL-60 in monocyte activation test. The method comprises the following steps: (1) preparing HL-60 cell suspension; (2) stimulating with pyrogen; (3) quantifying total protein; (4) detecting by Western blotting; and (5) evaluating cell function. The method is based on Western blotting technology, and combines statistical analysis to realize objective and quantitative determination of the core functional index of the ability of synthesizing IL-6 protein under pyrogen stimulation, can accurately identify cells with pyrogen response function defects, provides clear experimental reference for selection of HL-60 cell generations, can pre-screen qualified cells, reduces pyrogen detection deviation caused by unqualified cell function and improper generations from the source, and effectively improves the reliability and repeatability of pyrogen detection results.

The invention discloses PSE-like chicken breast composite gel soft food suitable for people with dysphagia and a preparation method of the PSE-like chicken breast composite gel soft food, and belongs to the field of food processing. The raw materials of the composite gel soft food comprise PSE-like chicken breast, konjac glucomannan and a sodium chloride solution, and the preparation method comprises the following steps: adding a mixed solution of konjac glucomannan and sodium chloride into PSE-like chicken breast, stirring, carrying out heating treatment after uniform stirring, and then cooling to obtain the PSE-like chicken breast composite gel soft food. The prepared food is stable in total protein content, can effectively make up for insufficient intake of meat protein caused by limited feeding of people with dysphagia, and prevents malnutrition; the product texture meets the swallowing requirement, reaches the IDDSI level 5 or level 6 standard, can effectively reduce the risk of food residue and aspiration in the swallowing process, and has nutrition balance and food safety.

The present invention has been made to solve the above-described problems of conventional MP whey, and an object of the present invention is to provide a protein material containing MP whey, which can be prepared by a simple method, does not contain extra additives, and has a wide range of applications, and a method for producing the protein material.SOLUTION: The present invention provides a method for producing a protein material containing MP whey, the method including: (1) a step of preparing a whey solution having a protein concentration of 11 mass% or less and a solid content concentration of 19 mass% or less; and (2) a step of shearing the whey solution prepared in the step (1) at 70 °C or higher and 95 °C or lower. The present invention also provides a protein material containing MP whey, wherein the MP whey has a median diameter of 2 μm or more and 9 μm or less, and the ratio of the mass of the MP whey protein to the mass of all proteins is 40% or more and 85% or less.SELECTED DRAWING: None

The invention belongs to the technical field of molecular biology, and relates to an application of transferrin (TF) as an internal reference protein in preparation of a reagent for detecting exosome proteins of neurodegenerative diseases. The TF can maintain a stable expression level in nerve cells, brain tissues, blood plasma and serum-derived exosomes of a subject suffering from neurodegenerative diseases, including Alzheimer's disease, mild cognitive impairment, amyotrophic lateral sclerosis, Parkinson's disease or Huntington's disease, and also including neurodegenerative diseases such as Alzheimer's disease, mild cognitive impairment, amyotrophic lateral sclerosis, Parkinson's disease or Huntington's disease. The TF expression variation coefficient is obviously lower than that of a common exosome marker, and the expression level of TF has stronger correlation with the total protein amount of the exosome and is not influenced by external factors such as cell inflammation stress. The TF as the internal reference protein has more excellent performance, can help to more accurately reflect the total loading amount of the sample, and provides a more stable and reliable standardized tool for the field of exosome research.

The invention relates to a method for extracting intracellular substances of microorganisms in cigar tobacco leaves. The method comprises the following steps: extracting thalli from cigar tobacco leaves; extracting nucleic acid and / or protein from the thalli; wherein the extraction method of the protein comprises the following steps: putting the thalli into a protein extraction buffer solution with the pH value of 7.0-8.5, and carrying out digestion at 40-50 DEG C to extract the protein; the extraction method of the nucleic acid comprises the following steps: putting the thalli into a nucleic acid extraction buffer solution, carrying out ultrasonication treatment for 10-60 minutes at 200-800 W, and extracting the nucleic acid. According to the method, high-purity and high-activity microbial total nucleic acid and / or total protein can be obtained from cigar tobacco leaves.

The invention belongs to the technical field of feed. The invention provides a feed for improving the color and luster of eggs and the content of natural carotene as well as a preparation method and application of the feed. The feed comprises a basal feed and a feed additive, wherein the feed additive comprises blakeslea trispora and chili powder. The egg yolk chromaticity of eggs and the content of beta-carotene in the egg yolk can be remarkably improved. Meanwhile, the total egg protein content can be increased, the total cholesterol and moisture content can be reduced, and the technical effect of improving the egg quality is achieved.

The invention discloses a recombinant duck plague virus protein combination, a subunit vaccine as well as a preparation method and application of the subunit vaccine, and belongs to the technical field of vaccine preparation. According to the technical scheme, the recombinant duck plague virus protein combination comprises recombinant gE protein and recombinant gI protein; the amino acid sequence of the recombinant gE protein is as shown in SEQ ID NO: 10, and the amino acid sequence of the recombinant gI protein is as shown in SEQ ID NO: 13. The nucleotide sequence of the nucleic acid molecule for coding the recombinant gE protein is as shown in SEQ ID NO: 12; the nucleotide sequence of the nucleic acid molecule for coding the recombinant gI protein is as shown in SEQ ID NO: 15. The duck plague subunit vaccine provided by the invention adopts gE and gI co-expression, only contains part of antigens of DPV, does not contain genetic materials, does not have toxin expelling and dispersing risks, is good in safety, can enable the spatial conformation of gE protein to be close to that of natural protein by co-expression of gE and gI, can realize 10 / 10 protection of challenge, has the total protein expression amount of about 4000 [mu] g / ml, and can be used for preparing a vaccine for the duck plague. The culture medium can be diluted by 40 times for seedling production, so that the production cost is greatly reduced.

The invention discloses a method for improving the stability of peanut butter, and belongs to the technical field of food processing. The invention provides a solution aiming at the problems that the peanut butter is easy to separate out grease and harden in texture in the storage process. The method comprises the following steps: by taking peanut protein powder as a raw material, preparing peanut protein isolate by an alkali-solution and acid-isolation method; measuring the contents of protein, fat and water in the peanut kernels, selecting baking temperature and time according to the measurement result, baking, removing red skin, and grinding to obtain a peanut butter base material; measuring the wet basis protein content and the moisture content of the peanut butter base material, selecting the addition amount of the peanut protein isolate in a range of 2-3% of the mass of the base material, and adding the peanut protein isolate into the base material to enable the wet basis total protein content of the mixture to reach 30-33%; and finally, stirring and mixing the mixture, and standing to obtain the stabilized peanut butter. The method is mainly used for improving the grease separation problem of the peanut butter and improving the storage stability of the peanut butter.

The exosome-glucan compound preparation provided by the invention comprises a stem cell exosome, the final concentration of the stem cell exosome in the exosome-glucan compound preparation is 1 * 10 < 8 > parts / mL to 1 * 10 < 12 > parts / mL based on particle concentration quantification or 1 mu g / mL to 500 mu g / mL based on exosome total protein quantification, and the final concentration of the stem cell exosome in the exosome-glucan compound preparation is 1 * 10 < 8 > parts / mL to 1 * 10 < 12 > parts / mL based on particle concentration quantification or 1 mu g / mL to 500 mu g / mL based on particle concentration quantification. The dextran is used as a matrix entrapment stem cell exosome, the weight-average molecular weight of the dextran is 10kDa to 5000kD, and the weight / volume percent of the dextran in the exosome-dextran compound preparation is 0.5% to 20%; glucan is used as a biocompatible matrix, and a lipid bilayer structure of the glucan wraps the stem cell exosome to form a physical protection barrier, so that the stem cell exosome is prevented from being degraded and inactivated in an in-vitro storage or in-vivo complex environment; and the degradation rate of the glucan matrix is matched with the wound healing period, so that long-acting slow release of the exosome is realized, and the bioavailability of a focus part is improved.

The present application relates to the biomedical field, disclose a kind of method for removing vitamin D in horse serum, comprising: material screening;25(OH)D in horse serum is physically adsorbed using selected material;After physical adsorption, horse serum is centrifuged;After centrifugation, horse serum is filtered using filter membrane;Selected material is dextran treatment modified activated carbon, dextran treatment modified activated carbon is repeatedly obtained by immersing treatment of modified activated carbon in saturated dextran solution;The mass ratio of dextran and modified activated carbon is 2-10:1;Modified activated carbon is obtained by bonding hydrophobic activated carbon using nitric acid pretreatment activated carbon and diphenyl dimethoxysilane, then using phytic acid to treat hydrophobic activated carbon and calcining to make, the method is efficient, low cost, can remove 25(OH)D in horse serum in scale, it also has high specificity, only remove 25(OH)D, retain total protein in horse serum;Simple operation, without complex equipment.

The invention relates to methods and kits for assessing brain injury, e.g., traumatic brain injury resulting from blast exposure. The invention provides methods of quantifying the amount of phosphorylated tau or total tau in a biological sample. The invention further provides a method of determining the number of blast exposures experienced by a subject. Also provided herein are kits for detecting phosphorylated tau or total tau in a biological sample.

To provide a processed food containing a meat-like ingredient mainly made of plant raw materials and having a meat-like richness imparted thereto, and a method for producing the same. [Solution] A heat-treated, containerized processed food containing a meat-like ingredient, wherein the meat-like ingredient is primarily made of plant-based ingredients including plant protein, and the processed food further contains acetic acid bacteria cells, the plant protein content of the total protein being 90% by mass or more, the mass ratio of the bacterial cells to the plant protein being 0.0005 or more, and the aldehyde dehydrogenase specific activity per 1 mg of the bacterial cells in a dry state being 0.1 U / mg or less.

The invention provides selenized pleurotus geesteranus polysaccharide as well as a preparation method and application thereof. The preparation method comprises the following steps: step 1, extracting pleurotus geesteranus polysaccharide from pleurotus geesteranus; 2, the pleurotus geesteranus polysaccharide reacts with Na2SeO3 and nitric acid, then alcohol precipitation is conducted, and the selenized pleurotus geesteranus polysaccharide is obtained. The selenium element can be successfully introduced into the pleurotus geesteranus polysaccharide structure through selenylation modification, the sulfate content and the selenium loading capacity of the polysaccharide are remarkably improved, and the content of total polysaccharide and the content of total protein are not subjected to obvious negative effects. The obtained selenized pleurotus geesteranus polysaccharide has excellent antioxidant activity and blood fat reducing activity at the same time, can be used as a functional additive, and has a good application prospect in blood fat reducing and antioxidant health-care food and medical products.

The invention relates to pediococcus pentosaceus CAR6 for improving carotenoid, protein peptide and plant-based flavor and application of the pediococcus pentosaceus CAR6. The preservation number of the pediococcus pentosaceus CAR6 is CGMCC (China General Microbiological Culture Collection Center) The strain has the acid stability fermentation characteristic, can avoid the problem of over-acidification caused by over-fermentation, can efficiently synthesize short-chain fatty acids such as organic acid and butyric acid, has good agglutination and self-agglutination capacity, oxidation resistance and SOD enzyme secretion capacity, and has a remarkable bacteriostatic effect on streptococcus mutans, staphylococcus aureus and shigella sonnei. When the carrot fermentation broth is applied to carrot fermentation, earthy smell and grass smell of raw materials can be effectively removed, the sensory flavor of a fermented product is remarkably improved, meanwhile, the content of carotenoid, total protein and polypeptide is increased, and the content of glucose is reduced. The strain provides a new bacterium source for fermentation of carrots and other plant-based products, and has important application value in development of flavor fermentation products, eye protection, sugar control, protein peptide and intestinal tract conditioning type healthy nutritional food.

The application discloses a pichia pastoris bioengineering bacterium for relieving degradation of recombinant collagen, a preparation method and application thereof. Through bioinformatics analysis, gene knockout and function verification screening, three protease genes capable of relieving degradation of collagen in a pichia pastoris host are obtained, namely, chr1-4_0611, chr1-4_0362 and chr2-2_0380. Knocking out the protease chr1-4_0611 can make the total protein yield accumulation increase to 3.5 times of that of a control bacterium, and the proportion of a target band is greater than 50%, which can provide good theoretical and technical guidance for effective expression of other recombinant proteins in the pichia pastoris host.

The invention belongs to the technical field of cartilage extracts, and particularly relates to application of a salmon nasal cartilage extract in preparation of a product for improving bone mineral density. The preparation method of the extract comprises the following steps: 1) performing low-temperature extraction on salmon nasal cartilage homogenate by using guanidine hydrochloride, centrifuging, and dialyzing to intercept total protein with the molecular weight of more than 8000; 2) adding precooled acetone into the total protein for fractional precipitation, and freeze-drying to obtain fractional precipitation protein; 3) dissolving the fractional precipitation protein in diluted hydrochloric acid, adding trypsin, and carrying out light-shielding enzymolysis to obtain an enzymatic hydrolysate; and (4) carrying out hydroxyapatite ion chromatography on the enzymatic hydrolysate, and carrying out ultrafiltration to intercept components with the molecular weight of less than 3kDa, so as to obtain the salmon nasal cartilage extract. The extract can significantly improve the multiplication capacity of embryo osteogenesis cell strains, can improve the bone mineral density value of shin bones of SD rats, has wide application prospects in the fields of food, health care products and medicines, and is especially suitable for development of bone health related products.

This invention discloses the application of a peptide SRD in the preparation of drugs for treating acute lung injury, belonging to the field of biomedical technology. In vivo experiments verified the protective effect of peptide SRD on acute lung injury (ALI), particularly its effect on improving AT2 mitochondrial function. In animal models of ALI, tail vein injection of peptide SRD significantly reduced the protein concentration and total cell count in bronchoalveolar lavage fluid, significantly alleviated the severity of lung injury, lowered histological scores, significantly decreased SOD2 acetylation levels while significantly increasing total SOD2 protein levels, and significantly increased SPC levels (an indicator of AT2 survival). ELISA analysis showed a significant decrease in the levels of IL-6, IL-1β, and TNF-α, indicators of pneumonia in mice. These experimental results confirm that the antioxidant peptide SRD can improve oxidative stress damage in ALI, effectively reduce AT2 cell damage under ALI conditions, promote AT2 regeneration and repair, effectively improve lung function, and reduce the inflammatory response of damaged lungs, thus exhibiting a good therapeutic effect on ALI.

This invention discloses a method for preparing steady-state and highly absorbable phycocyanin particles, relating to the fields of nutritional composition preparation and oral delivery technology. The method involves adjusting the phycocyanin stock solution into a buffer system and continuously passing it into an immobilized neutral protease microreactor. Online endpoint control is performed based on the absorbance ratio of 620 nm to 280 nm, the increase in free amino nitrogen, and the increase in fluorescence response. Contact is terminated and separation occurs when the proportion of homologous chromopeptides reaches 8% to 30% of the total protein nitrogen, yielding a complete phycocyanin-enriched component A and a homologous chromopeptide-enriched component B. Component B forms a chromopeptide composite nanodispersion, and component A forms a central core precursor. These components are coaxially sprayed to construct a three-layer radial structure particle consisting of a central core, an intermediate layer, and a shell, and then dried to obtain the composition. This method can improve the protective properties of phycocyanin in the oral gastrointestinal environment, enhance the gastric encirclement and retention characteristics and the sequential release characteristics in the intestinal segment, and provide more favorable release conditions for subsequent digestion and absorption.

The invention discloses a method for enhancing the synthetic ability of yeast total protein and dipeptide tripeptide. Relates to the technical field of synthetic biology and metabolic engineering. According to the invention, the saccharomyces cerevisiae engineering strain with high protein synthesis capability and high endogenous dipeptide and tripeptide accumulation level is successfully constructed. The metabonomics analysis reveals the unique peptide fragment accumulation spectrum, especially the generation of a large amount of lysine-rich tripeptide at the C terminal, and proposes a potential mechanism of metabolic pathway'bottleneck 'caused by peptidase activity down-regulation in combination with proteome data. The recombinant strain has important application potential in the fields of single-cell protein, functional peptide products and the like.

The invention provides an embryonic stem cell differentiation technology and application of the embryonic stem cell differentiation technology in screening of unknown risk alternative toxicity of a novel biological breeding product, and Cry1Ab protein is used as a test substance to evaluate the developmental toxicity of the Cry1Ab protein. The EBs are generated through hanging drop culture, and bone differentiation induction substances (beta-glycerophosphate, ascorbic acid and vitamin D3) are added to promote differentiation of the EBs. After bone cell induced differentiation is finished, the differentiation condition of bone cells is observed through alizarin red S dyeing and absorbance value detection, the cell growth condition is observed through cell total protein concentration and alkaline phosphatase activity detection, and then the influence of a test substance on the bone differentiation process is analyzed through the gene expression condition of osteogenic differentiation related markers (Runx2, SPARC and I-type collagen). The invention solves the problem of evaluating the unknown risk of a novel biological breeding product in vitro, creates an embryonic stem cell bone differentiation test technology, and uses the embryonic stem cell bone differentiation test technology as a screening method for the unknown risk alternative toxicity of the novel biological breeding product to be combined with an embryonic stem cell myocardial differentiation experiment for use. And the accuracy of predicating the developmental toxicity of the test substance is improved.

The application discloses an immune regulation pharmaceutical effect analysis method based on a concentrated pill of psammochloa and astragalus, which comprises the following steps: raw material extraction, animal model construction, multi-dimensional detection and data statistics. The raw materials of psammochloa and astragalus are weighed according to a specific ratio, and then are prepared into extract by ethanol decoction and concentration. After the experimental animals are grouped and administered intragastrically, the individuals are screened by the four oxygen pyrimidine modeling. The immune organs are separated, weighed, and the index is calculated. The contents of various cytokines in serum and liver tissue are detected by the ELISA method. The tissue morphology, lymphocyte proliferation and protein expression are observed by HE staining, MTT method and immunofluorescence method. The expression of key signal pathway proteins is detected by electrophoresis and other steps after the total protein is extracted, and statistical analysis is carried out. The method is systematic and comprehensive, the result is accurate and reliable, and a scientific basis is provided for the immune regulation pharmaceutical effect evaluation of the concentrated pill.

The invention relates to the technical field of animal feed preparation, in particular to animal feed rich in protein and a preparation method thereof. The animal feed provided by the invention is prepared by taking the chemically induced and intensively cultured microalgae as a protein source, modifying the protein source through succinylation and then synergistically compounding the modified protein source with a composite chelating agent. The content of microalgae protein in the feed prepared by the method reaches 20% or above of dry weight, the total protein content of the feed is greater than or equal to 28%, the protein digestion and absorption rate of animals is increased to 88% or above, and meanwhile, the animal immune function is effectively enhanced.

We provide nutritionally fortified products that allow for easy and consistent protein intake with every meal. [Solution] A product added to food for nutritional fortification, characterized in that: the product contains 95% by weight or more of whey protein isolate (WPI) powder with a protein content of 90% by weight or more; the proportion of low molecular weight protein components in the total protein content of the WPI powder is less than 1%; the low molecular weight protein components are the protein components that pass through the filter when an aqueous solution of the WPI powder is centrifuged using a centrifugal ultrafiltration filter with a nominal fractionation molecular weight of 10 kDa, and which exhibit coloration by the bicinchonic acid (BCA) method; and the proportion is a value obtained by determining the absorbance of the aqueous solution of the WPI powder before centrifugal filtration (A) and the absorbance of the filtrate after centrifugal filtration (B) using the BCA method, dividing B by A and expressing it as a percentage.

The application relates to the technical field of bioactive peptide preparation, and discloses a preparation method of a rhizoma polygonati peptide for anti-inflammatory and kidney protection, which comprises the following steps: (1) crushing rhizoma polygonati and then pretreating the rhizoma polygonati with an ethanol solution to obtain a water extraction concentrate; (2) adding the water extraction concentrate into a buffer solution to extract total rhizoma polygonati protein; (3) subjecting the total protein solution to enzymolysis with an enzyme, wherein the enzymolysis conditions are as follows: the enzyme concentration is 2%-5% of the mass of the substrate, the pH range is 7.5-8.5, the temperature is 45-55 DEG C, and the time is 35 hours; (4) after the enzymolysis solution is subjected to ultrafiltration to remove macromolecular impurities, a target peptide segment is separated through metal-modified medium dynamic coordination, the target peptide segment is purified through countercurrent distribution chromatography, and the rhizoma polygonati peptide is prepared through freeze-drying. The application is better used as anti-inflammatory and kidney protection raw materials through the complex enzyme synergistic enzymolysis, multi-site dynamic regulation and dynamic coordination separation technology, and is used for preventing and assisting in treating kidney-related diseases.

The invention discloses a HIV (human immunodeficiency virus), HBV (hepatitis B virus), HCV (hepatitis C virus) and TP (total protein) hypersensitive detection kit and detection method based on a digital PCR (polymerase chain reaction) platform. The kit comprises a primer and a probe, the design of the primer and the probe is optimized, and the molecular detection system has higher sensitivity by utilizing high affinity and strong mismatch recognition capability of the LNA probe, so that a single copy can be detected. The method possibly has huge potential in the aspects of large-scale screening and clinical diagnosis of blood donors and epidemiological research of pathogens.

A method for endogenously extracting a Mycobacterium smegmatis protein nanocage is provided. The method includes the following steps: introducing a recombinant plasmid containing a CFP29 gene and a 1×Flag affinity tag into a Mycobacterium smegmatis strain to obtain a recombinant Mycobacterium smegmatis strain; extracting a total protein solution of the recombinant Mycobacterium smegmatis strain, and subjecting the total protein solution of the recombinant Mycobacterium smegmatis strain to Flag tag affinity column chromatography purification to obtain a crude extract of the Mycobacterium smegmatis protein nanocage; and subjecting the crude extract of the Mycobacterium smegmatis protein nanocage to gel exclusion chromatography purification to obtain a pure product of the Mycobacterium smegmatis protein nanocage. The method is simple to operate and convenient to implement during extraction and purification, and an obtained Mycobacterium smegmatis background protein nanocage has a high yield, excellent purity, and stable properties.